A vacuum glass formed by compounding a plurality of glass plates gains attention owing to excellent sound proof and heat insulating performances thereof, and also becomes a research subject.
In the past, the edges of glass plates were sealed by using various plastics or resin materials to prepare the vacuum glass. For example, organic glass such as PC, ABS, LDPE, PVC and the like referred in certain patents is used as a sealing material, sandwich glass materials of PVB, EVA (EN) and the like are adopted in certain patents, and the processing method for the materials comprises the steps of putting the material between two glass plates, preparing the material into a prefabricated element together with the glass plates and pressing the prefabricated element under proper conditions to realize sealing of the edges of the glass plates. Such process is similar to a process for making sandwich glass; though compound sealing between the glass plates can be realized, the gas permeability and the moisture permeability of most plastics and resin materials are much greater than those of the glass; moreover, most organic materials are only bonded with the surfaces of the glass plates physically, so it is difficult to ensure no leakage at the bonded sections; and once gas (comprising water vapor) is permeated, weakening of the sealing strength, dew formation in the sandwich layer and glass mildew are directly occurred. In addition, as time goes on, the aging problem of the organic materials also directly affects the service life of the vacuum glass. Therefore, the method has gradually faded out the fabrication of the vacuum glass.
Later, a frit with a low melting point is used as a sealing material for making the vacuum glass, namely the frit with the low melting point is placed at the positions to be sealed on the edges of two adjacent glass plates, and the frit with the low melting point is melted by means of flame or electrical heating so as to air-tightly connect the edges of the two glass plates. The frit with the low melting point adopted in the process is generally a lead-zinc series (PbO—ZnO) glass material, and such a material has environmental protection risk in long-term use since lead metal is harmful to the environment and human health; meanwhile, the glass plates sealed by using the process will generate boundary heat stress, thereby needing an additional proper annealing treatment which greatly lowers the production efficiency and improves the processing cost; particularly, the heating temperature during sealing in the process is generally about 400-500° C., so if the process is used for making curved vacuum glass, the curved glass must be placed in a mold, otherwise, the original shape of the curved glass is destroyed and the curved glass cannot be normally sealed owning to deformation; and when the mold is used for sealing, the process and the equipment are complex, and the production efficiency is low because only a single piece of curved glass is produced in the same time. As an important type of glass product, the curved glass is greatly required in reality, so how to process the curved vacuum glass becomes a subject to be solved.